Mechanical timing device



April 11, 1961 P, QKSTEIN ET AL 2,978,983

MECHANICAL TIMING DEVICE Filed April 10, 1958 2 Sheets-Sheet 1 INVENTOR5 UL OKST IP A. STU

fiw W I ATTYS.

April 11, 1961 OKSTEIN ET AL 2,978,983

MECHANICAL TIMING D FIG.3.

INVENTORS PAUL OKSTEIN PHILIP ASTUDER NIECHANICAL TIMING DEVICE PaulOkstein, Brooklyn, N.Y., and Philip A. Studer, Lancaster, Pa.,assignors, by mesne assignments, to the United States of America asrepresented by the Secretary of the Navy Filed Apr. '10, 1958, Ser. No.727,755

2 Claims. (Cl. 102-79) This application relates generally to mechanicaltiming devices and more particularly to an inertia device for arming orfiring a projectile.

It is an object of this invention to provide a timing mechanism for usein ordnance that possesses dependability of action and is completelysafe during handling and storage.

Another object of this invention is to provide a mechanism for arming aprojectile as soon as it has travelled a given distance from thelauncher.

Still another object is the provision of a fuze timing mechanism forincorporation into an ordnance projectile or the like which mechanism issimple and of rugged construction.

Yet another object is the provision, in a mechanical timing device for aprojectile of a rotary member having a moment of inertia which isaltered by the spin of the projectile thereby providing a predeterminedtime delay.

An additional object of this invention is the provision of a rotatingmember carrying a portion of a fuze powder train of a bomb orprojectile, the member being adapted to rotate with respect to theprojectile housing to align the fuze train in active detonating relationat a predetermined time after the projectile is fired.

A further object of this invention is the provision of a rotatable shaftor rotor within a rotating ordnance projectile so that the difierencebetween rotational velocity of the rotor and the remainder of theprojectile produces a displacement between the shaft and the member in agiven interval of time. This rotational displacement is utilized tobring a member of a chain of charges into alignment, make or break anelectrical circuit, or act as a trigger to release other mechanism.

Older methods of accomplishing a time delay in the arming or detonationof an explosive projectile utilize unbalanced rotors which turn due tocentrifugal force. Other types employed balls moving radially outward inspiral grooves to exert a torque on an internal shaft thereby turningit.

These methods were subject to the disadvantage that complex gear trainsand escapement mechanisms were necessary to achieve the requiredrotational velocity, and in the case of the balls moving in the spiralgrooves, complex machining operations were necessary to produce thespiral grooves.

Generally the apparatus of this invention includes a shaft free torotate and disposed within a rotating cas Patented Apr. 11, 1961 iceinto a particular position, trigger a secondary mechanism after adefinite period of time, or make or break an electrical circuit after adefinite time.

The operation of this invention will be more readily understood when thefollowing specification is read in conjunction with the attendantdrawings wherein like numerals designate like or similar partsthroughout the several views and in which:

Fig. 1 is a longitudinal section of a typical inertia timing mechanismdisposed within a projectile or shell and shown in the unarmed position;

Fig. 2. is a longitudinal section of the inertia timing mechanism ofFig. 1 showing the apparatus in the intermediate position;

Fig. 3'is a longitudinal section taken along line 3-3 of Fig. 4 andshowing the inertia timing mechanism in the final or armed position; andFig. 4 is a section taken along line 4-4 of Fig. 1.

Referring now to the drawings in more detail, it is seen that theinertia timing assembly is composed of a casing 11 and an adapter plate12 threadedly secured into a projectile indicated generally at 13. Alsodisposed within the projectile 13 is a fuze shown schematically as abattery 14 and a switch 16 serially connected across a resistor 17fitted within an open ended bore 18 in adapter plate 12. A quantity ofprimer explosive 19 is also disposed within this bore for initiationupon closing of the switch 16.

A pair of aligned recesses 21 and 22 are formed within adapter plate 12and casing 11 respectively to provide a seat for bearings 23. Rotativelydisposed in these hearings is the rotor shaft 24- which is preferablymount ed concentrically with respect to the axis of spin or rotation ofprojectile 13 so that upon firing of the projectile the shaft 24 tendsto rotate at the same speed as the projectile. Accordingly, there is noinitial relative motion between the casing 11 and adapter plate 12 onthe one hand and shaft 24 on the other.

Disposed within an appropriate recess 26 in casing 11 is a perforatedrotor 27 having a perforated ring 28 secured to its outer periphery andwhich is fixed to shaft 24 for rotation therewith. A plurality ofinertia weights 31 are disposed within the guideways 29 formed in rotor27 at equi-angular intervals to prevent dynamic unbalance of the systemwhen the projectile rotates as it moves through the air.

A plurality of setback pins 32 are disposed in the rearward end of therecessed portion of rotor 27 and are urged forwardly by a soft biasingspring 33. These pins normally project into guideways 29 and fit intoappropriate recesses 34 in the inertia weights 31 to prevent them fromflying radially outward and prematurely arming the projectile.

Disposed in the lowermost portion of casing 1 1, in alignment withprimer 19 in adapter plate 12 is a bore 30 containing a quantity ofexplosive lead 35, while a quantity of detonator explosive 36 isdisposed within the ing, and carrying a plurality of weights which arereleasthrough bore 37 formed in therotor 27 so that when the explosives35, 36 and 19 are mutually aligned, firing of the primer 19 willinitiate the main charge indicated at 33. A blind arcuate groove 39 isformed in the rearward surface of adapter plate 12 while a projectingfinger 41 is fixed to the rotor 37 for movement within this groove.Accordingly, the rotation of rotor 27 with respect to casing 11 islimited by the length of groove 39 which length is selected so that whenthe finger 41 reaches the end of the groove, primer 19, lead 35 anddetonator 36 are in alignment.

Operation Figs. 1 through 3 show the sequence of operation of thisdevice from the unarmed position to the armed position.

Prior to firing, the setback pins 32 are disposed within the recesses 34in the respective inertia weights 31 to restrain outward movement ofthese weights. The setback force produced by firing of the projectileurges pin 32 rearwardly against the biasing force of spring 33,withdrawing the pins from inertia weights 31 allowing the weights tomove radially outward in the respective guide portions 29 of rotor 27.The perforations 20 in the rotor permit the air in the rotor to beinstantaneously redistributed to prevent undue cushioning of weights 31as they move outwardly.

Prior to the commencement of the radial outward movement of the inertiaweights, shaft 24 and rotor 27 rotate at the same speed as the rotationof the projectile so that there is no relative rotation between theshaft 24 and the remainder of the assembly. However, upon radial outwardmovement of inertia element 31 the moment of inertia of the rotorincreases. Since the product 1w [moment of inertia angular velocityprior to outward movement of elements 31] must equal the product 1 m[moment of inertia angular velocity after movement of weights 31] due tothe law of conservation of momentum and since I is greater than I, 011must become less than to. In other words, when the inertia weights arein their radially outwardmost position, the angular velocity of therotor shaft 24 and rotor 27 decreases. Although the inertia weights arerelatively heavy with respect to the rotor and rotor shaft, compared tothe total weight of the shell or projectile the weights are relativelyinsignificant. Accordingly, the angular rotational velocity of the shellis not materially altered by the change in inertia of the timingassembly.

Since the rotor 27 is now rotating at a different speed than theremainder of the casing 11, the shaft 24 begins to rotate within thecasing until the finger 41 reaches the end of the blind arcuate groove39 thereby preventing further relative motion between the rotor andcasing 11. At this time the detonator explosive 36 in the rotor isbrought in alignment with the lead 35 and the primer 19. Accordingly,when switch 16 is closed, the main explosive charge 38 will be ignitedby the now continuous powder chain. The rotating finger 41 itself mayalso be used to break or make an electrical contact as it moves throughgroove 31 to provide an optional method of electrically arming theprojectile if it is so desired.

Although we have described this invention with reference to but oneparticular embodiment it is not to be construed as so limited but issusceptible of many alterations and modifications. Accordingly, thescope of the invention disclosed herein is to be determined by the scopeof the appended claims only.

v What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. An inertia time delay mechanism for use in a projectile comprising; ahollow casing aflixed within the projectile for rotation therewith, ashaft rotatably disposed within said casing, a balanced rotor having aplurality of radial guideways therein and aflixed to said shaft, a pairof mutually aligned detonating elements disposed within said casing andinitially mutually separated by said rotor, a plurality of inertiaweights each slideably disposed within a respective guideway in saidrotor in a manner to maintain substantial balance of the rotor and topromote initial conjunct rotation of the rotor and the casing, saidinertia weights being slideable radially outwardly upon rotation of saidprojectile, thereby to change the moment of inertia of said shaft andsaid rotor to effect relative movement between said rotor and saidcasing, means disposed within said rotor adapted to operatively connectsaid detonating elements in said casing upon a predetermined movement ofsaid rotor relative to said casing.

2. An inertia time delay mechanism for use in a spinning projectilecomprising; a hollow casing having a blind internal groove thereindisposed within said projectile, a shaft rotatably disposed within saidcasing along the axis of spin of said projectile, a rotor having aplurality of radial guideways therein atfixed to said shaft, a pair ofdetonating means disposed within said casing and mutually separted bysaid rotor, intertia means disposed within the guideways in said rotorfor freely sliding radial outward movement upon spinning of saidprojectile thereby changing the moment of inertia of said rotor todecrease the speed of rotation of said rotor and effect continuousrelative rotational movement between the rotor and said casing, therelative rotational movement continuing after the radial outwardmovement of said inertia means ceases, stop means fixed to said rotorand operatively disposed within the groove in said casing to limitrotation between said rotor and said casing to a predetermined amount,means disposed within said rotor and adapted to provide an explosiveconnection between said pair of detonating means upon the predeterminedmovement of said rotor relative to said casing.

References Cited in the file of this patent UNITED STATES PATENTS1,567,232 Brayton Dec. 29, 1925 2,711,695 Williams June 28, 19552,834,292 Viasmensky July 6, 1956

